Understanding the growth factor requirements specific for transformed cells may lead to the growth regulation or destruction of these cells. This research proposal calls for the purification and chemical-biological characterization of a low molecular weight serum growth factor ("Peak III") of SV3T3 cells, a mouse fibroblast cell line transformed by an oncogenic DNA virus, Simian Virus 40. Preliminary studies suggest that Peak III, which specifically affects the growth of SV3T3 and not non-transformed 3T3 cells, is an oligopeptide. The investigation will characterize the chemical nature (by enzymatic, chemical, and spectroscopic methods) of Peak III and determine the chemical constituent(s) necessary for biological activity. To uncover the biological mechanism of this growth factor, the mitotic rate and the synthetic rates of various cellular components (DNA, RNA, protein, lipids) will be examined under conditions of Peak III depletion and supplementation. Since cis unsaturated fatty acids also independently limit SV3T3 cell growth, the rates of nutrient transport will also be monitored under conditions of unsaturated fatty acid and/or Peak III supplementation-depletion. Finally, attempts will be made to find methods and agents which antagonize the action of this transformed cell growth factor. BIBLIOGRAPHIC REFERENCES: Young, D.V. 1976. The Partial Replacement of the Serum Growth Factor Requirement of SV3T3 Cells by Lactalbumin Hydrolyzate. J. Cell. Physiol., 89: 133-142. Messmer, T.O. and D.V. Young, 1977. The Effects of Biotin and Fatty Acids on SV3T3 Cell Growth in the Presence of Normal Calf Serum. J. Cell. Physiol., 90: 265-270.